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h=Date:From:To:Cc:Subject:References:In-Reply-To; b=P7SEFFP8puwZXZp/YRq5bm12kLhga+lgh99B8rQeYLWPKvjGgDXAgg7amgbvop6gs KnFbcm9PWiLs6fpRX3X9ZFziRD/tbsK3eH/C4U9q+apMvreDXnEx9yuMWrWXaAlfn9 RfE+EypR5zdZI4scQXJRBlRBhEahbdQVPKXgYGzRzl4sArWd1u++y7ARbEBAYmsoti qa/YYnJeh63FtQSZKwP6986LY6PCjMAcEQlpM6IXvbI4ROaA1SfUtvjcxi9CnB5UZH Nk9IDitG/j2LUr0suo0oUruy11Tq+byoKby/mpiq0sCo0dpWi4sYmz38BnnJLGVmE9 9mRRThkgaqcJA== Date: Tue, 1 Sep 2026 10:59:16 +0300 From: Mike Rapoport To: David Laight Cc: Eli Billauer , Arnd Bergmann , Brad Warrum , Greg Kroah-Hartman , Michal Simek , Ritu Agarwal , Andrew Morton , David Hildenbrand , Matthew Wilcox , Vlastimil Babka , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org Subject: Re: [PATCH 2/4] char: xillybus: replace __get_free_pages() with kmalloc() Message-ID: References: <20260830-char-misc-v1-0-05e2ce44f291@kernel.org> <20260830-char-misc-v1-2-05e2ce44f291@kernel.org> <20260831123937.32255a49@pumpkin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260831123937.32255a49@pumpkin> X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6DF0D40002 X-Stat-Signature: 1i15coofeefs8kq7x3dumn8f4hbzjzxi X-HE-Tag: 1788249565-874435 X-HE-Meta: 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 WAoZyaO7 CGCkV4CNRVewMUVtvDt/r77NAbpobaywww6+ihuRF0m4g5rx04vIwu8P6spZkYlWnTvMzlgkGUgn8XIwibhO47n1BfBCwnDQ7Hvnsczq57r0iSXASCM4BSsvnR/Q2rftMMJ6RhOHTzgKnQ6vcjwXlcixQMdrCiuSHV9AQlkKV15WVd5040hUAUSHvvLS+CTp+G+WlUutqGgZlM0qKnPDos31NtKjXo+mPpwteh3NZ2nkdu5zclLRXnoQoBsJj86b1db6Oe+DVp7umAXD/280yawpnGtxUQUlZQZNoLcbbco0OIB8JaGBQPx1GsxpbRB4kYEeCU8TuREQHdtbQKK6ep3+36iYYD/NW34O+K0qVFUx4+holDcSdiguhBkYk6V6Au+Lo9aYUAjQiuQw2Cl5Z8IZu5g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Aug 31, 2026 at 12:39:37PM +0100, David Laight wrote: > On Mon, 31 Aug 2026 12:13:08 +0200 > Eli Billauer wrote: > > > On 30/08/2026 9:47, Mike Rapoport (Microsoft) wrote: > > > fifo_init() allocates the buffers backing the software FIFO and > > > endpoint_alloc() allocates the transfer buffers of a USB endpoint. > > > > > > These buffers can be allocated with kmalloc() as there's nothing special > > > about them to go directly to the page allocator. > > > > Except that they are a bit large. > > > > fifo_init() may be requested to allocate up to 256 MB of buffer memory. > > This memory resource is split into an array of buffers (fifo->mem[i]), > > each 64 kiB (or less, if there's trouble obtaining segments of this size). > > Would it really make sense to allocate the four buffers separately? > And/or use vmalloc(). My understanding is that the buffers don't need to be physically contiguous and vmalloc()ing the entire fifo->mem in one go should work. Eli, what do you think? > David -- Sincerely yours, Mike.